mate... that only applies (or is worth doing) when you are using human readable CSS... when it is minified like this then editing it in a file isn't any easier/better. the end result is the same - it gets compiled into a static string into JS code anyway... so the difference is whether you "feel" better about it being in a ClientBundle in minified form and then you can edit there as opposed to within the widget. In this case where the style is tightly coupled to the widget then there is marginal benefit.